The present disclosure relates to a power amplification circuit.
It is known that distortion is generated in the output signal of a power amplification circuit that employs a transistor and it is generally required that the distortion of the output signal be suppressed over a wide range of output levels. With respect to this requirement, for example, International Publication No. 2009/125555 discloses a power amplification circuit that detects the amplitude of the envelope signal of an input signal by using a detection diode in a bias circuit and suppresses the size of the bias current to a greater extent as the amplitude of the envelope signal increases.
The distortion characteristics of the output signal are dependent on both the output level and the frequency, and although the distortion characteristics of the output signal are improved over a wide range of output levels in the circuit disclosed by International Publication No. 2009/125555, it is difficult to improve the distortion characteristics of the output signal over a wide range of frequencies.